Chain cutter for debranching and debarking trees

ABSTRACT

A chain cutter for debarking and debranching tree trunks and having a plurality of roller members which engage the trunks and which are connected together with a plurality of links to form a link chain. A plurality of cutting teeth are fixed to the outer links of one side face of said chain, one portion of these teeth having cutting edges projecting beyond their associated link towards the trunk, and terminating approximately at a point which is on a line with the points of engagement of an associated roller and the trunk.

United States Patent Inventors Georg Wehr;

Gotthold Gotze, Rotenburg an der Fulda, Germany Appl. No. 620,925

Filed Mar. 6, 1967 Patented Mar. 2, 1971 Assignee RotenburgerMetallwerke Gmbll Fulda, Germany Priority Mar. 9, 1966 Germany 1142786CHAIN CUTTER FOR DEBRANCHING AND DEBARKING TREES [56] References CitedUNITED STATES PATENTS 1,759,188 5/1930 Davidson 144/208 1,937,07311/1933 Stuve....... l44/208(-8) 2,948,311 8/1960 McCollum.. 143/32(-4)2,707,007 4/1955 Shuff 144/208(-35) Primary Examiner- Donald R. SchranAttorney-Stevens, Davis, Miller & Mosher 10 Claims, 13 Drawing Figs.

US. Cl 144/208, 144/2, 143/32, 143/135 Int. Cl B271 1/00, B27b 33/14Field of Search 144/208- PATENTEU MAR 2197;

SHEET 1 BF 4 PATENTEDHAR 2m: 3,566,938

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2 2 7 I \zlwmm W4 INVENTORS Georg Wehr A ORNEYS CHAIN CUTTER FORDEBRANCHING AND DEBARKING TREES BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to a chain cutter and, moreparticularly, to a chain cutter for debranching and debarking trees.

2. Description of the Prior Art In the production of timber, it isnormal procedure to debranch and debark the trees immediately after theyhave been cut, and before they are transported to the sawmill or to theconsumer, in order to avoid attack by insects, and to facilitatehandling.

At the present time, the debranching and debarking of the felled treetrunks is generally performed mostly by hand with an axe, saw or peelingknife, This not only is time consuming, but often is difficult since thetree trunk has to be worked on from all sides, and therefore results ina relatively large labor expense. Accordingly, various equipment hasbeen developed, by which at least mechanical debarking of the felledtree trunks is performed in order to simplify the timber production andincrease output, the trunks having been debranched beforehand.

Apparatus is also known which simultaneously debranches and debarks, andwhich utilizes a chain cutter as the cutting tool. In these arrangementsthe chain cutter comprises a link chain which fonns a carrier element,and which either completely encloses the tree trunk, or at least engagesa portion of its periphery. However, many difficulties are encounteredin those known devices, which difficulties largely result from the factthat the trunk of a tree is generally not a perfect cylindrical bodywith a straight axis, but is rather an extended object often having anaxis which is substantially curved in various directions. Also, the treetrunks usually have a cross section which in addition to decreasing indiameter from the foot of the tree to its top, is completelyasymmetrical and has bumps and recesses of various shapes, in additionof course, to branches projecting from the surface of the trunk.

SUMMARY OF THE INVENTION These problems are solved with the apparatus ofthe present invention which features the use of cutting teeth disposedon the outer links of the chain, at least a portion of the teeth havingtheir cutting edges projecting beyond the associated chain link towardsthe trunk and terminating approximately at a point which is on a linepassing through the points of engagement of a chain roller which isadjacent the cutting edge and the tree trunk. In this way the problem ofthe chain cutter or its cutting teeth into the surface of the tree trunklying below the bark, is eliminated when tree trunks having varyingdiameters are encountered.

According to a further feature of the invention, at least threedifferent shaped and ground teeth follow one another on the outer links,each tooth extending in a direction perpendicular to the longitudinalaxis of the chain link. This results irr optimum cutting power andsimplifies the removal of the shavings.

It is particularly advantageous to construct the cutting teeth as solidteeth, and a satisfactory path for the chain is achieved if according toa further feature of the invention, the cutting edges of the teeth runparallel to the side faces of the chain links and perpendicular to theirlongitudinal axes. As a result, both the digging of the the chain intothe the trunk, and the lifting of the chain out of the bark as a resultof centrifugal force, is prevented. Jamming of the chain cutter whencutting through the branches is also eliminated with the presentinvention by arranging another portion of the teeth so that theircutting edges project away from the trunk and beyond the tangent whichis common to the two rollers associated with the teeth. Also, it isadvantageous if, in various successive teeth, the cutting edges of theteeth overlap when looked at in the longitudinal direction of the chain.

Satisfactory results are obtained with cutting teeth of a height of atleast 5 between 6 and 33 teeth per meter. and with chains havingAccording to a further feature of the present invention, the cuttingteeth each have a top rake and an upper clearance angle of approximately10,the inner tooth and the middle tooth having a clearance angle on thetrunk-engaging side from the cutting edge to the foot of the tooth ofapproximately 5 or 56, a clearance angle on that side which is remotefrom the trunk from the cutting edge to the foot of the tooth ofapproximately 258, and on both sides with a clearance angle from thecutting edge against the direction of movement of approximately 26.Also, the outer tooth may have a clearance angle on that side which isremote from the trunk from the cutting edge to the foot of the tooth ofapproximately 10, a lateral clearance angle on the side facing away fromthe trunk from the cutting edge against the direction of movement ofapproximately 5, and a lateral clearance angle on that side which facesthe trunk, from the cutting edge against the direction of movement, ofapproximately 2%.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the present inventionis described in the following by way of example in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagrammatic side view of a member of a link of the cuttingchain according to the present invention engaging a tree trunk, thechain link being provided with a cutting tooth;

FIG. 2 is a diagrammatic side view of an embodiment of the chain cutteraccording to the invention in an extended condition;

FIG. 3 is a diagrammatic end view in the direction of movement of thechain according to the present invention engaging a tree trunk;

FIGS. 4a to 4i show three different cutting teeth of the chain accordingto the present invention, each in plan view, end elevation, and sideview; and

FIG. 5 is a longitudinal sectional view of part of the chain accordingto the present invention in an extended condition, the section planecontaining the axis of rotation of rollers 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 to 3 and 5,the chain cutter 1 comprises a link chain serving as a carrier andincluding rollers 2, outer links 3, inner links 4, and intermediatelinks 5. Solid cutting teeth 6, 7 and 8 are mounted on the outer links 3of the one side face of the chain.

In FIG. 1 there is illustrated a chain cutter member which includes tworollers 2 engaging the trunk 9 to be debarked, and an outer link 3provided with a cutting tooth 6 on its face, the arrow 10 showing theperipheral direction movement of the chain to which the member belongs.Tooth 6 is mounted on the link 3 in such a manner that its cutting edge11 terminates approximately at a point 12 which is on a line with thepoint ofengagement between the upper surface of the trunk 9, and theroller 2 which is adjacent to the cutting edge.

As shown in FIG. 1, the spacing of the point of engagement 12 from thestraight line 14, which extends perpendicular to the longitudinal axis15 of the link 3 and passes through the axis of the roller 2, variesonly slightly with varying diameters of tree trunk, as shown, forexample, by surface 16 of a tree trunk having a larger diameter than thetrunk 9. This prevents tooth 6 from cutting into the surface of the treetrunk, even if the latter has a varying diameter.

The position shown in FIG. I for the cutting edge ll of the tooth 6 isindependent of whether only one form of tooth is used in the chaincutter, or whether, as shown in FIG. 2, various forms of teeth areemployed.

Referring specifically to FIG. 2, there are shown a few links and rollermembers of a chain cutter with three differently shaped forms of cuttingteeth provided on the links. As shown, an inner tooth 6, intermediatetooth 7 and outer tooth 8, are

provided on successive links 3. However, the teeth do not necessarilyhave to be arranged in the order shown in FIG. 2, but rather could bemountecht varying spacings, such as for example, on very second, thirdor fourth link.

The arrow 17 in FIG. 2 shows the peripheral direction of travel of thechain, and as can be seen in FIGS. 2, 3 and 4, the cutting edges 11 ofthe teeth 6, 7 and 8, which are mutually staggered perpendicular to thelongitudinal axis 15 of the link 3, overlap one another when looked atin the direction of travel of the chain. These edges also extendparallel to the side faces of the link 3 and perpendicular to thelongitudinal axis 15 thereof.

The outer teeth 8 have their cutting edges 11 projecting away from thetrunk and beyond the tangent 18 to the two associated rollers 2, asshown in FIGS. 2 and 3. In this manner, jamming of the chain cutter 1 asit passes through the base ofa branch 19 is avoided, even though thechain debranches and debarks simultaneously, this jamming beingotherwise liable to happen when the base 19 of the branch has a diameterwhich is larger than the width of the chain, as shown in FIG. 3. Thecutting edge of outer tooth 8 thereby cuts the chain 1 free so that itsunimpeded movement is insured. The axial movement of the chain unit inrelation to the trunk 9 is indicated in FIG, 3 by arrow 20, the feed ofthe chain being at right angles thereto, or outward from the plane ofthe drawing.

The teeth 6, 7 and 8 illustrated in FIGS. I to are solid teeth and havea height 2I which is always greater than 5 mm.

Preferably the cutting teeth 6, 7 and 8 are formed, ground and mountedon the links 3 as shown in FIGS. 40 to 4!. The teeth 6, 7 and 8 have atop rake 22 and an upper clearance angle 23 which are equal toapproximately The inner teeth 6 and intermediate teeth 7 each have aclearance angle 24 on that side which faces the trunk from the cuttingedge 11 to the foot of the tooth of approximately 5 or 2 18, a clearanceangle 25 on that side which faces away from the trunk to the cuttingedge I] to the foot ofthe tooth of approximately 29?, and on both sideswith a clearance angle 26 from the cutting edge 11 in a directionopposite to the direction of travel of the chain of approximately 2%.The outer teeth 8 have a clearance angle 27 on that side which facesaway from the trunk from the cutting edge 11 to the foot of the tooth ofapproximately 10, a lateral clearance angle 28 on that side which facesaway from the trunk from the cutting edge 11 in a direction opposite tothe direction of travel of approximately 5, and a lateral clearanceangle 29 on that side which faces the trunk from the cutting edge llopposite to the direction of travel of approximately 2%.

Links 3 with cutting teeth 6, 7 and 8 could be distributed along thechain I so that there results an overall number of teeth of from 6 to 33teeth per meter of chain length. In FIGS. 40, 4f, and 4i, arrows 30 showthe axial movement of teeth 6, 7 and 8 in relation to the trunk 9 to betreated, the feed of the chain, of course, being at right anglesthereto, as shown by the arrows I0 and 17 in FIGS. I and 2,respectively.

The chain cutter of the present invention thus works effectively,insures trouble-free debarking and simultaneous debranching of trees ofvarying diameters, and neither has an inclination to cut into the trunk,nor to become jammed when passing through the bases of large branches.

It is to be understood that the chain cutter of the present inventioncan be mounted on, and driven by, any conventional mechanism. Aparticularly suitable mechanism is disclosed in applicants copendingU.S. Pat. application Ser. No. 620,926 titled Apparatus for Transportingand Treating Trees, filed concurrently herewith.

Of course, variations of the specific construction and arrangement ofthis type chain cutter herein disclosed can be made by those skilled inthe art without departing from the invention as defined in the appendedclaims.

We claim:

1. A chain cutter comprising a plurality of roller members adapted toengage an object to be cut, and a plurality of links connected with saidroller members to form a link chain, wherein the improvement comprises aplurality of cutting teeth fixed to the outer links of one side face ofsaid chain, at least one portion of some of said teeth each having acutting edge projecting beyond its associated link towards said object,and terminating approximately at a point coincident with the point ofengagement of an associated roller and said object.

2. The chain cutter of claim 1, wherein said plurality of cutting teethis divided into three groups of teeth mutually staggered with respect tothe longitudinal axes of said outer links.

3. The chain cutter of claim 1, wherein said teeth are solid.

4. The chain cutter of claim 1, wherein the cutting edge of each of saidteeth extends parallel to the side faces of its corresponding outerlinks and perpendicular to the longitudinal axis thereof.

5. The chain cutter of claim I, wherein another portion of said teethhave cutting edges projecting away from the object to be cut, and beyondthe outer surface of their associated rollers.

6. The chain cutter of claim 2, wherein cutting edges of said mutuallystaggered teeth overlap one another in a plane at right angles to thelongitudinal axis of said chain.

7. The chain cutter of claim I, wherein the height of each of said teethis at least 5 mm.

8. The chain cutter of claim 1, wherein the chain has from 6 to 33 teethper meter oflength.

9. The chain cutter according to claim 2, wherein each of said staggeredteeth have a top rake of approximately 10 and an upper clearance angleof approximately 10; wherein the inner tooth and intermediate toothhave, on that side facing said object, a clearance angle from thecutting edge to the foot of the tooth of approximately 5 and 2%, aclearance angle on the opposite side from said object from the cuttingedge to the foot of the tooth of approximately 292, and on both sideswith a clearance angle from the cutting edge in a direction opposite tothe direction of travel of 2 A; and wherein the outer tooth has aclearance angle on the side facing said object from the cutting edge tothe foot of the tooth of approximately 10, a lateral clearance angle onthe side remote from said object from the cutting edge in a directionopposite to the direction of travel of approximately 5, and a lateralclearance angle on the side of said object from the cutting edge in adirection opposite the direction of travel of approximately 2%.

10. A chain cutter for debranching and debarking tree trunks, comprisinga plurality of roller members adapted to engage the trunk, and aplurality of links connected with said roller members to form a linkchain, wherein the improvement comprises a plurality of cutting teethfixed to the outer links of one side face of said chain, one portion ofeach of said teeth having a cutting edge projecting beyond theassociated link towards the trunk, and terminating approximately at apoint which is coincident with the point of engagement of an associatedroller and the trunk, for debarking said tree trunk; and another portionof said teeth having cutting edges projecting away from the trunk andbeyond the outer surface of their associated rollers, for debranchingthe trunk.

1. A chain cutter comprising a plurality of roller members adapted toengage an object to be cut, and a plurality of links connected with saidroller members to form a link chain, wherein the improvement comprises aplurality of cutting teeth fixed to the outer links of one side face ofsaid chain, at least one portion of some of said teeth each having acutting edge projecting beyond its associated link towards said object,and terminating approximately at a point coincident with the point ofengagement of an associated roller and said object.
 2. The chain cutterof claim 1, wherein said plurality of cutting teeth is divided intothree groups of teeth mutually staggered with respect to thelongitudinal axes of said outer links.
 3. The chain cutter of claim 1,wherein said teeth are solid.
 4. The chain cutter of claim 1, whereinthe cutting edge of each of said teeth extends parallel to the sidefaces of its corresponding outer links and perpendicular to thelongitudinal axis thereof.
 5. The chain cutter of claim 1, whereinanother portion of said teeth have cutting edges projecting away fromthe object to be cut, and beyond the outer surface of their associatedrollers.
 6. The chain cutter of claim 2, wherein cutting edges of saidmutually staggered teeth overlap one another in a plane at right anglesto the longitudinal axis of said chain.
 7. The chain cutter of claim 1,wherein the height of each of said teeth is at least 5 mm.
 8. The chaincutter of claim 1, wherein the chain has from 6 to 33 teeth per meter oflength.
 9. The chain cutter according to claim 2, wherein each of saidstaggered teeth have a top rake of approximately 10* and an upperclearance angle of approximately 10*; wherein the inner tooth andintermediate tooth have, on that side facing said object, a clearanceangle from the cutting edge to the foot of the tooth of approximately 5*and 2 1/2 *, a clearance angle on the opposite side from said objectfrom the cutting edge to the foot of the tooth of approximately 2 1/2 *,and on both sides with a clearance angle from the cutting edge in adirection opposite to the direction of travel of 2 1/2 *; and whereinthe outer tooth has a clearance angle on the side facing said objectfrom the cutting edge to the foot of the tooth of approximately 10*, alateral clearance angle on the side remote from said object from thecutting edge in a direction opposite to the direction of travel ofapproximately 5*, and a lateral clearance angle on the side of saidobject froM the cutting edge in a direction opposite the direction oftravel of approximately 2 1/2 *.
 10. A chain cutter for debranching anddebarking tree trunks, comprising a plurality of roller members adaptedto engage the trunk, and a plurality of links connected with said rollermembers to form a link chain, wherein the improvement comprises aplurality of cutting teeth fixed to the outer links of one side face ofsaid chain, one portion of each of said teeth having a cutting edgeprojecting beyond the associated link towards the trunk, and terminatingapproximately at a point which is coincident with the point ofengagement of an associated roller and the trunk, for debarking saidtree trunk; and another portion of said teeth having cutting edgesprojecting away from the trunk and beyond the outer surface of theirassociated rollers, for debranching the trunk.